首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   6115篇
  免费   545篇
  国内免费   13篇
耳鼻咽喉   68篇
儿科学   213篇
妇产科学   100篇
基础医学   799篇
口腔科学   100篇
临床医学   747篇
内科学   1225篇
皮肤病学   32篇
神经病学   664篇
特种医学   311篇
外科学   989篇
综合类   41篇
一般理论   3篇
预防医学   392篇
眼科学   180篇
药学   508篇
  1篇
中国医学   3篇
肿瘤学   297篇
  2021年   106篇
  2020年   51篇
  2019年   86篇
  2018年   86篇
  2017年   82篇
  2016年   75篇
  2015年   72篇
  2014年   125篇
  2013年   172篇
  2012年   254篇
  2011年   259篇
  2010年   143篇
  2009年   159篇
  2008年   227篇
  2007年   221篇
  2006年   256篇
  2005年   241篇
  2004年   194篇
  2003年   181篇
  2002年   166篇
  2001年   165篇
  2000年   184篇
  1999年   137篇
  1998年   83篇
  1997年   68篇
  1996年   75篇
  1995年   67篇
  1994年   59篇
  1993年   68篇
  1992年   165篇
  1991年   138篇
  1990年   169篇
  1989年   152篇
  1988年   151篇
  1987年   151篇
  1986年   141篇
  1985年   145篇
  1984年   112篇
  1983年   100篇
  1982年   81篇
  1981年   65篇
  1980年   67篇
  1979年   88篇
  1978年   89篇
  1977年   92篇
  1976年   74篇
  1975年   58篇
  1974年   84篇
  1973年   79篇
  1970年   57篇
排序方式: 共有6673条查询结果,搜索用时 15 毫秒
51.
Testicular function after orchiopexy for unilaterally undescended testis.   总被引:4,自引:0,他引:4  
Testicular function was determined in 29 men, 21 to 35 years old, who had undergone orchiopexy for unilaterally undescended testis at four to 12 years of age. Serum testosterone and dialyzable testosterone concentrations of these men were not significantly different from those of a control group of 30 normal men, and their basal serum luteinizing hormone concentrations and serum luteinizing hormone responses to synthetic gonadotropin-releasing hormone were only slightly higher than those of the normal men. The mean sperm density of the patients, however, was only one third of that of the normal men (p less than 0.001). The mean serum follicle stimulating hormone response ro gonadotropin-releasing hormone of the patients was doubled that of the normal men (p less than 0.001). The data indicate that spermatogenesis may be abnormal after orchipexy, and suggest that men with unilaterally undescended testis may have bilateral testicular abnormality.  相似文献   
52.
A slide latex agglutination (SLA) assay was developed for rapid screening for Clostridium perfringens type A enterotoxin (CPE). SLA specifically detected CPE added to buffer or normal feces (sensitivity limit of 1 μg CPE/g feces). Using clinical fecal samples from C. perfringens food poisoning cases, a strong correlation was shown between (1) SLA results and results from other CPE assays and (2) between SLA results and illness status.  相似文献   
53.
54.
IntroductionThere are many described technique to performing laparoscopic inguinal hernia repair in children. We describe our outcomes using a percutaneous internal ring suturing technique.MethodsA retrospective review of patients under 18 years old who underwent repair between January 2014 - March 2019 was performed. A percutaneous internal ring suturing technique, involving hydro-dissection of the peritoneum, percutaneous suture passage, and cauterization of the peritoneum in the sac prior to high ligation, was used. p < 0.05 was considered significant during the analysis.Results791 patients were included. The median age at operation was 1.9 years (IQR 0.37, 5.82). The median operative time for a unilateral repair was 21 min (IQR 16, 28), while the median time for a bilateral repair was 30.5 min (IQR 23, 41).In total, 3 patients required conversion to an open procedure (0.4%), 4 (0.6%) experienced post-operative bleeding, 9 (1.2%) developed a wound infection, and iatrogenic ascent of testis occurred in 10 (1.3%) patients. Twenty patients (2.5%) developed a recurrent hernia. All but two were re-repaired laparoscopically.ConclusionsThe use of percutaneous internal ring suturing for laparoscopic repair of inguinal hernias in the pediatric population is safe and effective with a low rate of complications and recurrence.  相似文献   
55.
56.
Morphine sulfate effects (30 mg, intramuscularly) on cerebral glucose utilization and subjective self-reports were examined in 12 polydrug abusers by positron emission tomography and [fluorine 18]fluorodeoxyglucose in a double-blind placebo-controlled crossover study. During testing, subjects sat with eyes covered, listening to white noise and "beep" prompts. Morphine significantly reduced glucose utilization by 10% in whole brain and by about 5% to 15% in telencephalic areas and the cerebellar cortex, assuming no contribution of hypercapnia. When the contribution of PaCO2 (45 minutes after morphine was administered) was partialled out, significant morphine-induced reductions persisted in whole brain and six cortical areas. Irrespective of morphine, left-greater-than-right asymmetry occurred in the temporal cortex, and an interaction between hemisphere and drug was noted in the postcentral gyrus. In most cases, effects on glucose utilization were not significantly related to measures of euphoria.  相似文献   
57.
Many researchers interested in sexual orientation can be separated into two camps: The lumpers, who try to reduce sexual classifications to as small a number of categories as possible, and the splitters, who try to show differences among groups and individuals that make classification schemes increasingly difficult and/or intricate. We report factor analyses of the Klein Grid (a questionnaire with 21 sexual orientation items) to see how many factors emerge in two samples of strikingly different origins. In both samples, the first factor to emerge loaded substantially on all of the Klein Grid's 21 items. This factor accounted for a majority of the variance. In both samples, a second, correlated factor emerged which indexed a separation between most of the items and those having to do with social and/or emotional preferences. In both samples, a third correlated factor also emerged, but this factor differed between the two populations: one refined the social/emotional distinction and the other distinguished ideal behavior from past and current behavior. We conclude on the basis of our analysis that both the lumpers and the splitters are correct.Supported by NIMH grants IP50 MH 45294 and R01 MH 43298.  相似文献   
58.
59.
In their core curriculum guidelines, the Society of Teachers of Family Medicine has recognized the importance of training family physicians in caring for persons with mental retardation. We mailed surveys to all family practice residency directors in the United States, questioning them about experiences and methods used to teach residents about health care needs of adults with mental retardation and the importance of this education. We found that 84% of programs provide residents with one or more experiences, and 60% instruct residents in this area. Most directors ranked this education as very important or important. There was no relationship between type or age of residency program and likelihood that residents were educated about mental retardation. The importance of this education is discussed.  相似文献   
60.
Inositol 1,4,5-trisphosphate receptors (IP3R) are mediators of second messenger-induced intracellular calcium release. Three isoforms are known to be expressed in brain, but their regional distributions and cellular localizations are little known. In order to better understand the roles of IP3 receptor isoforms in brain function, a first step is to define their distributions. We have used affinity-purified antibodies directed against peptides unique to each isoform to determine their sites of expression in rat brain. Type 1 IP3R (IP3R1) is dramatically enriched in Purkinje neurons in cerebellum and neurons in other regions, consistent with previous studies. By contrast, IP3R2 is only detected in glia, whereas IP3R3 is predominantly neuronal, with little detected in glia. IP3R3 is enriched in neuropil, especially in neuronal terminals (which often contain large dense core vesicles) in limbic and basal forebrain regions including olfactory tubercle, central nucleus of the amygdala, and bed nucleus of the stria terminalis. In addition, IP3R1 and IP3R3 have clearly distinct time courses of expression in developing brains. These data suggest separate roles for inositol 1,4,5-trisphosphate receptor isoforms in development, and for glial and neuronal function. The IP3R3 may be involved in regulation of neurotransmitter or neuropeptide release in terminals within specific nuclei of the basal forebrain and limbic system.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号